The present invention relates to a power transmission system, an IC card and an information communication system using an IC card, wherein commutation tickets, railway tickets, bus tickets, etc. to be used at wickets in railway stations or on buses will be replaced with IC cards, and when an IC card is made to pass a reader/writer, being provided at a wicket in a railway station or on a bus, with noncontact or in close proximity to it, power can be transmitted from the reader/writer to the IC card by radio.
It has been known that power can be supplied to an IC card from a power supply side by a noncontact method using rays of light or magnetic fields.
When commutation tickets, railway tickets, bus tickets, etc. to be used at wickets in railway stations or on buses will be replaced with IC cards, and when a user passes an IC card through a reader/writer provided at a wicket in a railway station or on a bus with noncontact, the distance between the IC card and the reader/writer may vary much. When the reader/writer is so adjusted that proper power can be transmitted from the reader/writer to the IC card when the distance between the IC card and the reader/writer is comparatively large, then in a case where the distance between the reader/writer and the IC card is small, excessive power may be transmitted from the reader/writer to the IC card, which may cause a malfunction or breakage of the IC card.
In other words, in the prior art, careful consideration was not given to a point that proper power shall be stably transmitted to an IC card from a reader/writer even though the distance between the IC card and the reader/writer may be largely varied.
Prior art in which it is intended to stably supply power from a reader/writer to an IC card even if the distance between the IC card and the reader/writer is largely varied is explained in Japanese Patents Laid-open No. Hei 7-85233 and Laid-open No. 9-62816.
In the Japanese Patent Laid-open No. 7-85233, following are described: among noncontact type data carriers of electromagnetic coupling system, in the case of movable equipment having a function to be able to receive data including a control signal from fixed equipment, a rectifier circuit composed of a rectifier D1 and a capacitor C2, and a variable resistor element composed of a transistor T2, resistor R3 and resistor R4 being controlled by a DC voltage obtained from the rectifier circuit are connected to a receiving coil of the data carrier in parallel, and an excess power will be consumed in the variable resistor elements. Further it is described in the Japanese Patent Laid-open No. Hei 7-85233 that a signal detector circuit composed of a rectifier D2, a resistor R1 and a capacitor C3 which detects an amplitude-modulated wave superimposed on a AC voltage induced in the receiving coil and transmits the detected data to a main circuit of the data carrier as an input signal, and an amplitude modulator circuit which receives the output signal of the main circuit of the data carrier for switching a transistor T1, and being composed of the transistor T1 which transmits data from the data carrier to the fixed equipment, a capacitor C4 and a resistor R2 are connected to the receiving coil of the data carrier in parallel. In the prior art as mentioned in the above, a resonant circuit is not formed in the receiving coil of the data carrier, so that in a case where the distance between the transmitting coil on the fixed side and the receiving coil on the data carrier side is large, an enough voltage is not induced in the receiving coil and it is made difficult to obtain the power required by the main circuit of the data carrier. There is also another problem in the prior art. Since a half-wave rectifier is adopted in the prior art, a large ripple is produced, which requires a large smoothing capacity; therefore, it is made difficult to incorporate a capacitor of a large capacity in a data carrier in miniaturizing it.
It is described in the Japanese Patent Laid-open No. Hei 9-62816 that a receiving signal level of a resonance circuit of an antenna for transmitting and receiving data is detected and the quality factor Q of the antenna resonance circuit is varied by changing the variable resistor element according to the detected voltage in order to adjust a receiving signal level to a desirable value.
In these prior art, since a variable resistor element is directly connected to a receiving antenna in parallel, there is a problem in that the temperature rise in the variable resistor element is large and the size of a pressure protection circuit becomes large.
The purpose of the present invention is to solve the above-mentioned problems and offer an IC card and a power transmission system by radio in which it is made possible to stably supply power by radio from a reader/writer to the internal circuit of an IC card in miniaturizing the elements of a pressure protection circuit and decreasing the temperature rise in a variable impedance circuit provided in an IC card even though the distance between the IC card and the reader/writer may be largely varied.
Another object of the present invention is to offer an IC card and a power transmission system by radio in which the power can be stably supplied to the internal circuit of the IC card by radio from a reader and/or writer by only making the IC card pass the reader and/or writer with noncontact or in close proximity to it by improving the responsibility of the system in miniaturizing the elements in a pressure protection circuit and decreasing the temperature rise in a variable impedance circuit.
A further object of the present invention is to offer an IC card and an information communication system using an IC card in which it is made possible to supply power stably from a reader and/or writer to the IC card with noncontact in miniaturizing the elements in the pressure protection circuit and decreasing the temperature rise in the variable impedance circuit provided in the IC card and to perform information communication with high reliability between the reader and/or writer and the IC card.
Yet another object of the present invention is to offer a power transmission system by radio, an IC card and an information communication system using the IC card. In the power transmission system by radio it is so arranged that power can be stably supplied even when the distance between an IC card and a reader/writer is largely varied in decreasing the temperature rise in the variable impedance circuit by controlling the static capacity for the induced power received on the IC card side.
A still further object of the present invention is to offer a power transmission system by radio, an IC card and an information communication system using the IC card. In the power transmission system by radio it is so arranged that proper power can be stably supplied to the IC card by radio from the power transmission portion of the reader/writer by only passing the IC card through the reader/writer with noncontact or in proximity to it and information can be communicated between the reader/writer and the IC card with high reliability.
In order to achieve the above-mentioned objects, the present invention is a power transmission system in which power is transmitted by radio from a power transmitting device (reader and/or writer device) to an IC card. The IC card comprises: an antenna having a resonance circuit for receiving the transmitted radio wave, a full wave rectifier circuit for rectifying an induced power received by the antenna, a power supply circuit which converts a DC voltage output from the full wave rectifier circuit into a power supply voltage, a detector circuit which detects the DC voltage output from the full wave rectifier circuit, an impedance control circuit portion which produces a desired power supply voltage from the DC voltage detected in the detector circuit by controlling the impedance of the circuit, and an internal circuit to be supplied with the desired power supply voltage obtained from the impedance control circuit.
The present invention is also a power transmission system in which power is transmitted by radio from a power transmission device to an IC card, wherein the IC card comprises: a receiving portion which receives the transmitted radio wave and produces induced power, a rectifier circuit portion which converts the induced power in the receiving portion into a DC voltage, a variable impedance circuit portion in which the DC voltage obtained in the rectifier circuit is controlled by varying the impedance of the circuit based on the induced power detected in the detector circuit portion or a voltage corresponding to the induced power, and an internal circuit to be supplied with a controlled DC voltage from the variable-impedance control circuit.
The present invention is also a power transmission system in which power is transmitted by radio from the power transmission device to an IC card. In the IC card, the transmitted induced power is converted into a DC voltage, the transmitted induced power or a voltage corresponding to the induced power is detected, and a power supply voltage of a desired DC voltage to be supplied to the internal circuit is obtained by controlling a static capacity based on the detected induced power or a voltage corresponding to the induced power.
The present invention is a power transmission system in which power is transmitted by radio from a power transmission device to an IC card. The IC card comprises: a rectifier circuit which converts the transmitted induced power into a DC voltage, an internal circuit to be supplied with the DC voltage obtained from the rectifier circuit, a detector circuit which detects the transmitted induced power or a voltage corresponding to the induced power, and a static capacity control circuit which obtains a power supply voltage of a desired DC voltage to be supplied to the internal circuit by controlling the static capacity based on the induced voltage or a voltage corresponding to the induced power which is detected in the detector circuit.
The present invention is a power transmission system in which power is transmitted by radio from a power transmitting device to an IC card. The IC card comprises the functions as shown below: the transmitted induced power is converted into a DC voltage to be supplied to an internal circuit, the transmitted induced power or a voltage corresponding to the induced power is detected, and the information about the detected induced power or a voltage corresponding to the induced power is transmitted by radio to the power transmitting device. The power transmitted from the power transmitting device is controlled based on the above-mentioned transmitted information.
The present invention is a power transmission system in which power is transmitted by radio from a power transmitting device to an IC card. The IC card comprises the function to convert the transmitted induced power into a DC voltage and to supply the DC voltage to the internal circuit, and also to detect the information concerning the relative position of the IC card to that of the power transmitting device. The power transmitted from the power transmission device is controlled based on the above-mentioned detected information.
The present invention is a power transmission system in which power is transmitted by radio from a power transmitting device to an IC card. The IC card comprises the function to convert the transmitted induced power into a DC voltage and to supply the DC voltage to the internal circuit and to detect the information concerning the relative position of the IC card to that of the power transmitting device. A desired DC voltage can be obtained in controlling the impedance of a circuit in the IC card based on the detected information.
The present invention is an IC card which comprises: an antenna having a resonance circuit for receiving a transmitted radio wave, a full wave rectifier circuit for rectifying an induced power received with the antenna, a power supply circuit for converting the DC voltage obtained from the full wave rectifier circuit into a power supply voltage, a detector circuit for detecting the DC voltage rectified in the full wave rectifier circuit, an impedance control circuit which controls the impedance of the circuit for making the detected DC voltage a desired DC voltage and making the power supply voltage converted in the power supply circuit a desired power supply voltage, and an internal circuit to be supplied with the desired power supply voltage obtained from the impedance control circuit portion.
The present invention is an IC card which comprises: a receiver portion which receives a radio wave to produce an induced power, a rectifier circuit portion for rectifying the induced power generated in the receiver portion to convert the induced power to a DC voltage, a detector circuit portion which detects an induced power obtained in the receiver portion or a voltage corresponding to the induced power, a variable impedance control circuit portion which controls the DC voltage obtained from the rectifier circuit portion based on the induced power detected in the detector circuit portion or a voltage corresponding to the induced power, and an internal circuit to be supplied with a controlled DC voltage from the variable impedance control circuit portion.
The present invention comprises an IC card in which an impedance in the variable impedance circuit portion is formed with a resistor.
The present invention is an IC card in which the full wave rectifier circuit, the power supply circuit, the detector circuit, the impedance control circuit, and the internal circuit are composed with one chip.
The present invention is an IC card which comprises: a receiver portion which receives an induced power by radio, a rectifier circuit portion which rectifies the induced power received in the receiver portion to convert it into a DC voltage, a detector circuit portion which detects the induced power obtained from the receiver portion or a voltage corresponding to the induced power, a static capacity control circuit portion which obtains a desired DC voltage from the rectifier circuit portion by controlling the static capacity based on the induced power detected in the detector circuit portion or a voltage corresponding to the induced power, and an internal circuit which is supplied with a DC voltage from the rectifier circuit portion being controlled by the static capacity control circuit portion.
The present invention is an information communication system using an IC card which comprises a reader and/or writer device (unit) having an information communication portion and a power transmitting portion and power is transmitted by radio from the power transmitting portion to an IC card.
The IC card comprises: a rectifier circuit portion which rectifies the induced power transmitted from the reader and/or writer to convert the induced power into a DC voltage, a detector circuit portion which detects the induced power obtained from the receiver portion or a voltage corresponding to the induced power, a variable impedance control circuit portion which controls the impedance of the circuit according to the DC voltage obtained from the rectifier circuit portion based on the induced power detected in the detector circuit portion or a voltage corresponding to the induced power, and an internal circuit which obtains a desired DC voltage from the variable impedance control circuit. The information communication system is so designed that an information communication can be performed using a radio wave between the internal circuit of the IC card and the information communication portion of the reader and/or writer device.
Transmitted to the IC card or a voltage corresponding to the induced power is detected, and a desired DC voltage is obtained in controlling the impedance base on the detected induced power or a voltage corresponding to the induced power and the desired DC voltage is supplied to the internal circuit. The present invention is so constituted that it is possible to perform information communication by radio between the internal circuit of the IC card and the information communication portion of the reader and/or writer device.
The present invention is an information communication system using an IC card, which comprises reader and/or writer device having an information communication portion and a power transmission portion and power is transmitted by radio from the power transmitter portion to the IC card by radio. The IC card comprises: an antenna having a resonance circuit for receiving a radio wave transmitted from the reader and/or writer device, a full wave rectifier circuit for rectifying the induced power received in the antenna, a power supply circuit which converts the DC voltage rectified in the full wave rectifier circuit into a power supply voltage, a detector circuit which detects the DC voltage rectified in the full wave rectifier circuit, an impedance control circuit which controls the impedance of the circuit to make a detected DC voltage detected in the detector circuit a desired DC voltage and to make the power supply voltage converted in the power supply circuit a desired power supply voltage, and an internal circuit to be supplied with the desired power supply voltage obtained from the impedance control circuit.
The information communication system is so designed that the information communication can be performed by a radio wave between the internal circuit of the IC card and the information communication portion of the reader and/or writer device.
The present invention is an information communication system using an IC card which comprises a reader and/or writer device having an information communication portion and a power transmission portion which transmits power from the power transmission portion to the IC card by radio. In the IC card, following operations are performed: the induced power transmitted from the reader and/or writer device is converted into a DC voltage and it is supplied to the internal circuit, the induced power transmitted to the IC card or a voltage corresponding to the induced power is detected, and the information concerning the detected induced power or the voltage corresponding to the induced power is transmitted to the power transmission portion of the reader and/or writer device by radio. The reader and/or writer controls the power to be transmitted from the power transmission portion based on the information sent from the IC card. The information communication system is so designed that information communication can be performed between the internal circuit of the IC card and the information communication portion of the reader and/or writer device.
The present invention is an information communication system using an IC card, wherein the transmission of power by radio from the reader and/or writer to the IC card and the communication of information by radio between the internal circuit of the IC card and the information communication portion of the reader and/or writer device are performed with a common antenna.
The present invention is an information communication system, using an IC card, wherein the reader and/or writer device comprises: a power supply portion which generates a signal to be used for the transmission of power an encoder circuit for encoding input data for transmission, a modulator which executes amplitude modulation of a signal obtained from the encoder circuit and superimposes it on the signal obtained from the power supply portion, a feeder circuit for feeding power based on the signal obtained from the modulator, and an antenna for generating a radio wave corresponding to the fed current by the feeder circuit.
The present invention is an information communication system using an IC card, wherein the internal circuit of the IC card comprises: a decoder circuit which performs waveform shaping and decodes a modulated wave for communication detected by the antenna, a microcomputer which inputs received data decoded in the decoder circuit and outputs transmission data, an encoder circuit which encodes the transmitting data output from the microcomputer, and a modulator which modulates a signal and inputs it to the antenna based on the signal encoded in the encoder circuit.
As explained in the above, according to the above-mentioned constitution, it is made possible to realize a power transmission system by radio and an IC card, wherein even though the distance between the IC card and the reader and/or writer device (power transmitting device) is largely varied, power can be stably transmitted by radio from the reader and/or writer device to the internal circuit of the IC card in miniaturizing a pressure protection circuit provided in the IC card and decreasing the temperature rise in a variable impedance circuit. In particular, the realization of miniaturization of the elements of the pressure protection circuit and the low temperature rise in the variable impedance circuit made it possible to constitute an IC card with an antenna for receiving a radio wave and elements of one-chip constitution, which caused to realize a low cost IC card.
According to the above-mentioned constitution, a power transmission system by radio and an IC card can be realized, wherein power can be transmitted from the reader and/or writer device to the IC card by radio using a coil-shaped antenna or a spiral antenna on the IC card, and power can be supplied stably by radio from the reader and/or writer device to the internal circuit of the IC card by only making an IC card pass the reader and/or writer device with noncontact or in the proximity to it in miniaturizing the elements in the pressure protection circuit, decreasing the temperature rise in the variable impedance circuit, and improving the responsibility of the circuit.
According to the above-mentioned constitution, a power transmission system by radio, an IC card, and an information communication system using an IC card can be realized, wherein power can be stably supplied to the IC card even though the distance between the IC card and the reader and/or writer is largely varied in decreasing the temperature rise in the variable impedance circuit by controlling the induced power received on the side of the IC card by varying the static capacity in the variable impedance circuit.
According to the above-mentioned constitution, a power transmission system by radio, an IC card, and an information communication system using the IC card can be realized, wherein proper power can be transmitted from the power transmission portion of the reader and/or writer device to the IC card by radio by only making the IC card pass the reader and/or writer with noncontact or in proximity to it. Thus, power is stably supplied to the internal circuit of the IC card, and the communication of information of high reliability can be performed between the reader and/or writer device and the IC card.
According to the above-mentioned constitution, an information communication system using an IC card can be realized, wherein power is stably supplied from the reader and/or writer to the IC card with noncontact, and the communication (transmission and reception) of information of high reliability can be performed between the reader and/or writer device and the IC card.